let _Vue = null;
export class VueRouter {
    static install(Vue) {
        //1 判断当前插件是否被安装
        if (VueRouter.install.installed) {
            return;
        }
        VueRouter.install.installed = true;
        //2 把Vue的构造函数记录在全局
        _Vue = Vue;
        //3 把创建Vue的实例传入的router对象注入到Vue实例
        // _Vue.prototype.$router = this.$options.router
        _Vue.mixin({
            beforeCreate() {
                if (this.$options.router) {
                    _Vue.prototype.$router = this.$options.router;
                }
            },
        });
    }
    constructor(options) {
        this.mode = options.mode || 'history';
        this.options = options;
        this.routeMap = {};
        // observable
        this.data = _Vue.observable({
            current: '/',
        });
        this.init();
    }
    init() {
        this.createRouteMap();
        this.initComponent(_Vue);
        this.initEvent();
    }
    createRouteMap() {
        //遍历所有的路由规则 吧路由规则解析成键值对的形式存储到routeMap中
        this.options.routes.forEach((route) => {
            this.routeMap[route.path] = route.component;
        });
    }
    initComponent(Vue) {
        const self = this;
        Vue.component('router-link', {
            props: {
                to: String,
            },
            render(h) {
                return h(
                    'a',
                    {
                        attrs: {
                            href:
                                self.mode === 'hash' ? '#' + this.to : this.to,
                        },
                        on: {
                            click: this.clickhander,
                        },
                    },
                    [this.$slots.default]
                );
            },
            methods: {
                clickhander(e) {
                    if (self.mode !== 'hash') {
                        e.preventDefault(); // 阻止 a 标签的默认行为
                        history.pushState({}, '', this.to);
                    }
                    this.$router.data.current = this.to;
                },
            },
            // template:"<a :href='to'><slot></slot><>"
        });

        Vue.component('router-view', {
            render(h) {
                // self.data.current
                const cm = self.routeMap[self.data.current];
                return h(cm);
            },
        });
    }
    initEvent() {
        if (this.mode !== 'hash') {
            window.addEventListener('popstate', () => {
                this.data.current = window.location.pathname;
            });
        } else {
            window.addEventListener('load', () => {
                this.data.current = window.location.hash.slice(1);
                if (!this.data.current) {
                    this.data.current = '/';
                    window.location.hash = '#/';
                }
            });
            window.addEventListener('hashchange', () => {
                this.data.current = window.location.hash.slice(1);
            });
        }
    }
}
